Helical charge distributions

We consider the Coulomb potential due to a helical charge distribution at some distance d larger than the molecular dimensions of the assumed chiral charge distribution (see Fig. 2)... 

Table 4.14 Structure (top) and physical properties [41] table below) of semi-fluorinated n-alkanes (60-63) and the homologous dialkyl bicyclohexyl liquid c stals 64 and 65 from which they are structurally derived. The spacefill model of 63 shows the helical conformation of the central perfluoroalkylene segment in contrast with the pentyl side-chains with their typical hydrocarbon zigzag conformation. The differences in charge distribution (red and blue denote negative and positive partial charges, respectively) are visualized by mapping of the electrostatic potential on to the electron density of 63 (B3LYP/6-31C //PM3 level of theory) [44, 50].

Fig. 4. Structure of Escherichia coli photolyase. (A) Ribbon diagram representation. The MTHF antenna is exposed on the surface, whereas the FADH catalytic cofactor is buried within the core of the a-helical domain. (B) Surface potential representation. Blue, basic residues red, acidic residues white, hydrophobic residues. Note the positively charged groove running diagonally the length of the protein and the hole (marked by a square) with asymmetric charge distribution along the side walls and leading to the flavin located in the bottom. (See Color Insert.)...

Figure 7 The transient charge distributions for the 6xy xy transition of a twisted Mo2L4L 4 chromo-phore. On rotating the rear set of ligators through an angle of between 0° and 45° in the counterclockwise direction, the charge distribution is that of a left-handed helix. When the rotation is between 45° and 90°, the transition gives rise to a right-handed helical charge displacement.

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